Method for specifying engraving of a gravure cylinder for coatings containing particle dispersions

Abstract

A method of engraving a gravure cylinder having a circumference C for coating a liquid composition on a substrate. The liquid composition contains a concentration of particles having a predetermined particle diameter. The method includes calculating the engraving channel depth Do based on a first ratio of the particle diameter to channel depth (DB/Do). Then, engraving the gravure cylinder according to theta, alpha, WC, Ww, and Wo.

What is claimed is:  
     
       1. A method of engraving a gravure cylinder having a circumference C for coating a liquid composition on a substrate, said liquid composition containing a concentration of particles having a predetermined particle diameter, said method comprising the steps of: 
       (a) determining a coverage VA, of the liquid composition on the substrate;  
       (b) selecting a stylus angle θ;  
       (c) selecting a compression angle α;  
       (d) specifying a first ratio (D B /D o ) of said predetermined particle diameter D B  to an engraving channel depth D o ;  
       (e) calculating said engraving channel depth D o  based on said first ratio (D B /D o ) and said predetermined particle diameter D B ;  
       (f) specifying a second ratio (W w /W o ) of a wall width W w  to cell width W o ;  
       (g) calculating a channel width W c  according to equation  
       
         
             W   c =[2 tan θ/2] D   o    
         
       
       (h) calculating the cell width W o  according to the equation  
       
         
             VA =[1122.5/(tan θ/2)]*[3  W   o   2 +2  W   o   W   c +3  W   c   2 ]*[(2)/ X]   
         
       
        wherein X=W o +W c +2W w ;  
       (i) calculating the wall width W w  based on the second ratio; and,  
       (j) engraving the gravure cylinder according to θ, α, W c , W w , and W o .  
     
     
       2. The method according to claim  1  wherein the first ratio is less than 0.5 or greater than 1.1. 
     
     
       3. The method according to claim  1  wherein said particles have a predetermined diameter in the range of 1 micron to about 25 microns. 
     
     
       4. The method according to claim  1  wherein said particles have a predetermined diameter in the range of 6 microns to 16 microns. 
     
     
       5. A method for engraving a gravure cylinder having a circumference C for coating a liquid composition on a substrate, said liquid composition having a concentration of particles having a predetermined particle diameter, said method comprising the steps of: 
       (a) determining a coverage VA of the liquid composition on the substrate;  
       (b) selecting a stylus angle θ;  
       (c) selecting a compression angle α;  
       (d) specifying a first ratio (D B /D o ) of said predetermined particle diameter D B  to an engraving channel depth D o ;  
       (e) calculating said engraving channel depth D o  based on said first ratio (D B /D o ) and said predetermined particle diameter D B ;  
       (f) specifying a second ratio (W w /W o ) of a wall width W w  to cell width W o ;  
       (g) calculating a channel width W c  according to equation  
       
         
             W   c =[2 tan θ/2 ]D   o    
         
       
       (h) calculating the cell width W o  according to the equation  
       
         
             VA =[1122.5/(tan θ/2)]*[3  W   o   2 +2  W   o   W   c +3  W   c   2 ]*[(2)/ X ] 
         
       
       wherein X=W o +W c +2W w ; 
       (i) calculating the wall width W w  based on the second ratio;  
       (j) calculating engraving parameter according to θ, α, W c , W w , and W o    
       (k) calculating the horizontal repeat length X according to:  
       
         
             X=W   o   +W   c +2 W   w ;  
         
       
       (l) calculating a horizontal screen (HS) according to:  
       
         
             HS =2/ X    
         
       
       (m) calculating a line screen according to:  
       
         
             AS=HS 2/tan α 
         
       
       (n) calculating a vertical screen (VS) count according to:  
       
         
             VS=AS /(tan α*2);  
         
       
       (o) calculating an engraver vertical setting N 2  according to:  
       
         
             N   2   =C*VS /7.5; and,  
         
       
       (p) engraving the gravure cylinder according to N 2  and θ.  
     
     
       6. The method according to claim  5  wherein the first ratio is less than 0.5 or greater than 1.1. 
     
     
       7. The method according to claim  5  wherein said particles have a predetermined diameter in the range of 1 micron to about 25 microns. 
     
     
       8. The method according to claim  5  wherein said particles have a predetermined diameter in the range of 6 microns to 16 microns.